<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>测试</title>

    <style>
        div {
            display: flex;
            width: 60%;
            height: 150px;
            background-color: pink;
            margin: 0 auto;
        }
        
        div span :nth-child(1) {
            width: 100px;
            height: 150px;
            background-color: rebeccapurple;
        }
        
        div span :nth-child(2) {
            flex: 1;
            background-color: green;
        }
        
        div span :nth-child(3) {
            width: 100px;
            height: 150px;
            background-color: blue;
        }
    </style>
</head>

<body>

    <div>
        <span></span>
        <span></span>
        <span></span>
    </div>
</body>

</html>